Conocimientos, actitudes y prácticas sobre virus del papiloma humano, cáncer cérvico uterino y prevención / Knowledge, attitudes and practices on human papilloma virus, cervical cancer and prevention

Objetivo: Explorar los conocimientos, actitudes y prácticas ante el cáncer cervicouterino (CCU), el virus del papiloma humano (VPH) y sus formas de prevención entre las mujeres de 25 a 64 años de edad en el Salvador. Métodos: Se llevó a cabo un estudio descriptivo de corte transversal mediante una encuesta poblacional en una muestra probabilística y representativa de 838 mujeres de áreas urbanas y rurales de los departamentos de Santa Ana y Sonsonate. Se aplicó un cuestionario estructurado con 84 preguntas mayoritariamente cerradas o semi-abiertas, este cuestionario fue validado por expertos de la Unión Internacional de Cáncer Control...

Objective: To explore the knowledge, attitudes and practices of Salvadorian women between the ages of 25 and 64 regarding cervical uterine cancer, human papillomavirus (HPV) and their prevention. METHODS: We carried out a cross-sectional descriptive study by conducting a population survey with a probabilistic and representative sample of 838 women in urban and rural areas of the departments of Santa Ana and Sonsonate. We administered a structured survey that was previously validated by experts fron the Union for International Cancer control (IUCC). The questionaire consisted of 84 primarily closed and semi-open questions...

Human papillomavirus vaccines: current issues & future.

Cervical cancer is the leading cause of cancer mortality among women in worldwide. Some 99 per cent of cervical cancer cases are linked to genital infection with human papillomaviruses (HPVs) comprised of approximately 15 oncogenic genital HPV types. Most HPV infections resolve spontaneously. But, the remainder persist and may then progress to cervical cancer in some women. In high-resource countries, the best way to prevent cervical cancer is to implement organised gynaecological screening programs with appropriate treatment of the detected pre-cancerous lesions. However, in developing countries, this method is not practicable because of cost and complexity of proper screening. Vaccines against HPV infections hold promise to reduce incidence of cervical cancer cost-effectively. Two Prophylactic HPV vaccines have been thus far developed: Gardasil, a quadrivalent vaccine targeting HPV-6, -11, -16 and -18) and Cervarix, a bivalent vaccine which targets HPV-16 and -18. Both vaccines contain L1 virus-like particles (VLPs) derived from HPV-16 and -18 which are most frequently associated with cervical cancer. The L1-VLP vaccines are HPV type-specific and therefore can effectively prevent infection of a HPV type in question alone. Therefore, the L1-VLP vaccines are hoped to be multivalent for 15 oncogenic HPV types, which comes at a price. Otherwise, costly cytologic screening for cervical cancer is still necessary. The current HPV vaccines thus may not be ultimate strategy and study on new HPV vaccines is needed. Broad-spectrum prophylactic vaccines against all oncogenic HPV types and therapeutic vaccines for clearance of HPV-related cervical lesion are being developed.

Cervical cancer prevention & the role of human papillomavirus vaccines in India.

Human papillomavirus (HPV) is a necessary cause of cervical cancer, the leading cause of cancer deaths among Indian women. Current screening and prevention programs based on cytology have not been effective in reducing the disease burden. Two vaccines are now available for primary prevention. They generate neutralizing antibodies to HPV capsid protein. The vaccines have been shown to confer nearly 100 per cent protection against cervical pre-cancers and genital warts caused by HPV types 16/18 in HPV naïve population with few or no side effects. Though there is some cross-protection, around 30 per cent of cervical cancers will not be prevented by the vaccine. Vaccination and screening, which are complementary and synergistic, now constitute the new paradigm for prevention of this disease.

HPV & HPV vaccination: Issues in developing countries.

Cervical cancer is the second-most common cancer in women worldwide causing most cancer related deaths in women in developing countries including India. The most predominant etiological factor for cervical cancer is persistent infection of certain high-risk types of human papillomaviruses (HR-HPVs), while low-risk types are associated with benign cervical lesions and genital warts. In India, the most common (98%) oncogenic types are HPV types 16 and 18 with HPV 16 exclusively (80-90%) prevalent. Two recently developed virus-like particle (VLP) based prophylactic HPV vaccines, quadrivalent Gardasil (HPV 16/18/6/11) and Cervarix (HPV 16/18) offer great promise. Several other therapeutic vaccines are also in clinical trials and are yet to establish their efficacy. The use of already developed VLP vaccines in resource-poor regions is limited by several factors, most importantly the high cost of the vaccine. Therefore efforts are being made in India to develop cost-effective second-generation vaccines. Besides cost, there are several socio-cultural and ethical issues involved with the implementation of already developed vaccines including the acceptability of HPV vaccination by preadolescent girls and their parents in India.

HPV vaccination: the promise & problems.

Four-fifths of the cervical cancer burden in the world is experienced in developing countries. HPV genotypes 16 and 18 account for 70 per cent of cervical cancers and currently available vaccines targeting these two types confer a high degree of protection against HPV 16/18 infection and related cervical precancerous lesions. However, widespread implementation of HPV vaccination programs are challenged by the unaffordable high costs of the vaccines and the lack of effective vaccine delivery platforms for sexually naïve girls. Other unresolved issues include long-term protection, cross-protection against HPV types not included in the vaccine and whether booster doses will be needed. Sensitivities associated with a vaccine preventing a sexually transmitted infection in girls, lack of awareness, public demand and political will, lack of coordination between cancer control, sexual and reproductive health and vaccine delivery services are additional challenges. Reduced costs, simple vaccine regimes and strengthening vaccine delivery platforms for adolescents should eventually facilitate HPV vaccine introduction in developing countries.

Can cervical cancer be eradicated by prophylactic HPV vaccination: Challenges to vaccine implementation.

Cervical cancer is the first cancer to be shown to be 100 per cent attributable to a virus; oncogenic human papillomaviruses (HPV), particularly types 16 and 18, collectively worldwide contribute to 70 per cent squamous cell carcinomas, 85 per cent of adenocarcinomas. Cervical cancer is the second commonest cancer of women, yet largely preventable with high-quality, well-organized screening of the appropriate population. Screening programmes are either nonexistent, or function opportunistically in many poorer countries, resulting in high incidence and mortality. Recently developed, prophylactic HPV vaccines against HPV 16, 18, as cervical cancer preventative vaccines, in phase 3 clinical trials have been shown, to be highly efficacious, safe and immunogenic. With the potential for cross protection against related HPV types, estimates for prevention are in the order of 75 to 80 per cent. Thus a further option exists in the battle to reduce these cancers in women. Challenges however include implementing a vaccination programme with wide coverage to the target populations to be a successful public health tool, integration and maintenance of current screening programmes where they are in existence, the need for reduced costs of the current vaccines, long-term immunogenicity (will there be a need for further doses?), appropriate education messages to the general community, governments, as well as the medical profession.

Anti-human papillomavirus therapeutics: Facts & future.

Even after 25 years of establishing Human Papillomavirus (HPV) as the causative agent for cervical cancer, effective treatment of HPV infection still unavailable. Comprehensive efforts especially for targeting HPV infection have been made only in recent years. Conventional physical ablation of HPV-induced lesions such as cryo-therapy, photo-therapy, LEEP, laser cone-biopsy and localized radiotherapy are shown to be effective to some extent in treating localized lesions where the removal of diseased tissue is associated with removal of transforming keratinocytes harboring HPV. Apart from currently available prophylactic vaccines which prevent the viral entry and should be given prior to viral exposure, several attempts are being made to develop therapeutic vaccines that could treat prevailing HPV infection. In addition, immunomodulators like interferons and imiquimod that have been shown to elicit cytokine milieu to enhance host immune response against HPV infection. Also, antiviral approaches such as RNA interference (RNAi) nucleotide analogs, antioxidants and herbal derivatives have shown effective therapeutic potential against HPV infection. These leads are being tested in pre-clinical and clinical studies. Present article provides a brief overview of conventional therapies for HPV-associated diseases. Potential of non-ablative anti-HPV treatment modalities that could prove useful for either elimination of HPV in early stages of infection when the virus is not integrated into the host cell genome or suppression of the expression of viral oncogenes that dysregulate the host cell cycle following transformation is discussed.

Immune responses to human papilloma viruses.

HPV infection in the genital tract is common in young sexually active individuals, the majority of whom clear the infection without overt clinical disease. However most of those who develop benign lesions eventually mount an effective cell mediated immune response and the lesions regress. Regression of ano-genital warts is accompanied histologically by a CD4+ T cell dominated Th1 response; animal models support this and provide evidence that the response is modulated by CD4+ T cell dependent mechanisms. Failure to develop effective CMI to clear or control infection results in persistent infection and, in the case of the oncogenic HPVs, an increased probability of progression to CIN3 and invasive carcinoma. The central importance of the CD4+ T cell population in the control of HPV infection is shown by the increased prevalence of HPV infections and HGSIL in individuals immunosuppressed as a consequence of HIV infection. The prolonged duration of infection associated with HPV seems to be associated with effective evasion of innate immunity as reflected in the absence of inflammation during virus replication, assembly and release, and down regulation of interferon secretion and response thus delaying the activation of adaptive immunity. Serum neutralising antibody to the major capsid protein L1 usually develops after the induction of successful cell mediated immunity and these antibody and cell mediated responses are protective against subsequent viral challenge in natural infections in animals. Prophylactic vaccines consisting of HPV L1 VLPs generate high anti L1 serum neutralizing antibody concentrations and in clinical trials have shown greater than 95 per cent efficacy against both benign and neoplastic genital HPV associated disease. These vaccines are delivered intramuscularly and therefore circumvent the immune evasion strategies of the virus.

Genotypes of the human papillomavirus: Relevance to Indian field trials of the vaccine.

Highly effective HPV vaccines are likely to become available for use in India shortly. The availability and validation of the vaccines to prevent oncogenic HPV infection associated lesions from progressing to cancer has clearly offered a cost effective long-term strategy to reduce the cervical cancer burden, particularly for developing countries where effective screening programmes are not available. The enthusiasm for these new vaccines duly justified, are we in reality targeting the actual delinquent by prompting these vaccines in India? The answer would be no as we may not be essentially implementing a rational fool-proof vaccine program which will aid in preventing HPV-related diseases, for the simple reason that there is a lack of understanding about the underlying HPV types responsible for cervical cancer in India. Field trials involving large populations form a major part of continued analysis in understanding any disease and India is still short of such a trial as far as cervical cancer is concerned. Conducting such studies, might also act as prevention programs that will save lives and improve public health in a substantive manner.

Cervical cancer screening & HPV vaccination: a comprehensive approach to cervical cancer control.

India with its highest share of global burden of cervical cancer has to implement a population based cervical cancer control program to reduce the number of deaths. There are new screening options available like visual inspection after acetic acid application (VIA) test, single visit approach to screening and treatment etc. Emergence of the two effective vaccines against human papillomavirus (HPV), the necessary cause of cervical cancer, has introduced a fresh lease of life to the cervical cancer control strategies. The current high cost of the vaccines is a major impediment to implement a vaccine-based primary prevention approach.

Infection of human papillomaviruses in cancers of different human organ sites.

Clinico-epidemiological and molecular studies have established the casual link between Human Papillomavirus (HPV) infection and cervical cancer as also association of HPV infection with several other cancers. In India, cervical cancer is a leading cancer among women and almost all cases of cervical cancer show prevalence of High Risk (HR)-HPV infection. HPV has been also detected in a significant proportion of oral, esophageal, anal, vaginal, vulvar, and penile cancer and in a small percentage of lung, laryngeal, and stomach cancer in India. Due to lack of organized HPV screening program, insufficient infrastructure and trained manpower and inadequacy in cancer registries, there are not much data available on the countrywide HPV prevalence and its type distribution in different cancers in India. Forthcoming introduction of recently developed HPV vaccines in India given a new urgency to know the prevalence and distribution of various HPV types in different organ sites for the management and monitoring of vaccination program and its impact on prevalence of other cancers. This review, summarizes studies on the prevalence of HPV infection in cancers of different organ sites in India.